This invention relates to air conditioning units and more particularly to "Venturi" units in induced air systems for cooling or heating rooms in buildings such as office buildings, schools, libraries, banks, stores, and the like.
In recent years, air conditioning units of the "plenum diffuser" type have come into use as an alternative to both square and round diffusers. A plenum diffuser unit includes an inlet collar and a plenum chamber, integrated with a diffusion and directional device within the chamber for control of air distribution.
The plenum diffuser unit is mounted parallel in a ceiling runner of each room and usually extends about four feet in length. During operation, the unit produces a constant flow of heated or cooled air throughout the room. The advantage of the "plenum diffuser" over square and round diffusers is that it distributes air more evenly and follows the contour of the ceiling which adds to the aesthetics.
However, virtually all prior art plenum diffusers have a serious disadvantage in common. Once the damper is set, the plenum diffuser handles the same volume of air both entering and leaving. No means of continuous capacity control can be utilized while the unit is in operation. Even the more modern plenum diffusers which incorporate a means of varying the volume, (variable volume) has no means of introducing secondary air (return air) back into the unit. This means that when the volume dampers are almost closed and the primary air is reduced, the enclosure could suffer from air stratification due to lack of circulation.
With the induced air "Venturi" plenum diffuser, when the volume dampers are semi-closed, the conditioned air (primary air) is reduced, but through induction, secondary air (return air) is drawn back into the unit. The ultimate effect is that a higher volume of air maintains room air motion and the enclosure is brought to the desired temperature quicker.